my LPG changeover switch failed recently, leaving my motorhome stranded. I have removed it as a temporary measure so now running on petrol alone.

I have purchased a new switch after some searching but to my disappointment the connector on the rear is different. I don't have a wiring diagram for my system or the new switch so I am hoping someone can help me with the connections. I have Googled for hours but not found what I need.

The switch is a Landi Renzo LCS A1 V05 and i have tried to attached pics which show the old (6 pin) and new (4 pin) connectors. However, I got this message - "the board attachment quota has been reached". I can post photos if that gets sorted out.

Can't help with the switch even though it looks very similar to the standard AEB switch fitted to systems such as the Leonardo although they only have 4 pins and no intermediate position. To post photo's see here viewtopic.php?f=33&t=12009 as the board quota was reached years ago so it's much easier to host them on Photobucket or similar and just link to them.

What system are we talking about here? Is it a single point open loop? In which case all the control is done in the switch rather than by a separate controller so something like this http://tinleytech.co.uk/shop/lpg-parts/ ... b-engines/ could be fitted instead. It might need the loom changing as well but there's so little to it that it shouldn't be difficult.

The switch on the left is a stand-alone controller and has all the electronics to switch the LPG on and off, petrol on and off, cut off all fuel when the engine stops turning, etc. The switch on the right is just a dumb switch that can only be used in conjunction with a separate ECU controller... they're not interchangeable. The switch Gilbert linked to will be interchangeable with the switch on the left but will need to check pinout, would only involve swapping a few wires around in the loom to the rear of the switch at most. If you tell us the wiring colours on the plug at the back of your switch we'll be able to say which wires need to be swapped around if any.

Fixed a big RV the other day, owner arrived with 2 switches similar to the one on the left, had just bought a new one suspecting old one was broke but vehicle wouldn't run on gas with either switch. RV had just been undersealed... I went straight under the back to look around the tank area and immediately found the joint earth wire that the undersealer had broken, fixed in 5 mins lol... Then owner says 'I'd like to use the new switch but it shows empty and my tanks are full'... Another simple fix, I reprogrammed the switch to 0-90 level sender type.

The switch on the left is a stand-alone controller and has all the electronics to switch the LPG on and off, petrol on and off, cut off all fuel when the engine stops turning, etc. The switch on the right is just a dumb switch that can only be used in conjunction with a separate ECU controller... they're not interchangeable. The switch Gilbert linked to will be interchangeable with the switch on the left but will need to check pinout, would only involve swapping a few wires around in the loom to the rear of the switch at most. If you tell us the wiring colours on the plug at the back of your switch we'll be able to say which wires need to be swapped around if any.

Fixed a big RV the other day, owner arrived with 2 switches similar to the one on the left, had just bought a new one suspecting old one was broke but vehicle wouldn't run on gas with either switch. RV had just been undersealed... I went straight under the back to look around the tank area and immediately found the joint earth wire that the undersealer had broken, fixed in 5 mins lol... Then owner says 'I'd like to use the new switch but it shows empty and my tanks are full'... Another simple fix, I reprogrammed the switch to 0-90 level sender type.

Simon

If its easier send a photo and I'll put it on photobucket of the wiring connector showing the cable colours.

I have now ordered one of the switches in the link, which I hope will come with a wiring diagram. I hope also that Brian_H will kindly post photos of the existing connector (many thanks Brian), and the solenoids under the bonnet. As you will see, it is an old system ... but works pretty well!It will just be a case of wiring the switch correctly into my loom, and the switch looks like it comes with some wiring in any case. I may need to ask for advice when the switch arrives if it's not clear to me...Thanks for all the help so far, I wish I had come here sooner.

They are standard colours for a system like yours. Red wire is taking an ignition switched live to power it up, while the brown is picking up pulses to tell it the engine is turning over. The black wire will also be grounded or it won't switch on. Blue will go live when on gas and yellow will be live when on petrol. The only thing that has a question mark on it is the white wire to the level gauge. Simply connect it and it may work but you may need to tell the switch what sender type you have. Without knowing what the options are and what sender type you have, you might need to try a bit of trial and error.

I would suggest shunting the main power feed on the red wire through a relay.

The LPG system main feed would then come straight from the battery via the relay via a 7.5amp fuse, the switched live from the coil would then energise the relay (via a 3amp fuse). Running the couple of amps that it takes to energise the LPG system solenoid valves can place extra strain on the main feed to the ignition coil, and if there is ever a problem with the LPG system electronics (such as a shorted solenoid coil) there would be no potential for the problem to take out the ignition system...

If you have more than one tank on the motorhome (thus more than 2 LPG solenoid valves, one on each tank and one in the engine bay) I would also fit a relay to switch current to the LPG solenoid valves instead of the current coming directly from the blue wire.

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